This is a very early announcement advertisement for the Wang 700 Electronic
Calculator, which later became the 700-Series calculators. The Wang 700
calculator was announced over a year before it was actually available for sale,
a prime example of what later became termed as "vaporware". The reason for
the early announcement of a machine that existed only in a prototype form was
that in 1968, Hewlett Packard had introduced (and had real machines to sell)
the HP 9100A calculator, which took Wang Laboratories completely by surprise,
with the 9100A greatly surpassing Wang's highly-successful 300-Series
caclulators.

This ad shows a very early prototype (likely empty, or minimally populated with
just keyboard and display) using a front-loading cassette tape drive.
By the time the 700-Series calculators went into production, the cassette
drive was a pop-out top-loading device. Some keyboard arrangement changes
were also made in the production calculators.

See the Exhibit
for a Wang 700-Series calculator, or, for more information, read the
Article on Wang's calculator
(and calculator-based custom-systems) evolution.